Power actuators are motor/gear driven assemblies that pull cables which typically unlock and release locking mechanisms, and thereby allow a portion of a seat system to move/rotate. The actuators are mechanically back-driven to their initial starting positions, typically with a spring. A drawback to this approach is that the back-drive spring makes the motor and gears rotate quickly in reverse direction, producing a whining sound during return and a noticeably loud click when the gears reach their travel stop. More significantly perhaps is that the gear train is subjected to very high impact loading, and the gear teeth are vulnerable to fracture. To protect the gear train and minimize the clicking sound, rubber bumper stops are sometimes used. But the reverse whining sound is still present, and the bumpers are added expense. Return time is typically ½ second. A standard solution which places a diode across the motor terminals eliminates motor whine and gear tooth impact loading results in an undesirably long return time (˜5 seconds).
Accordingly, there is a need for improved vehicle seat actuators with improved sound and time performance.